Explosive motors



Feb. 15, 1966 H. c. FILER EXPLOSIVE MOTORS Filed Nov. 4, 1964 FIG. I

WWW/z United States Patent M 3,234,727 EXPLOSIVE MOTORS Harold Curtis Filer, Xenia, Ohio, assignor to The National Cash Register Company, Dayton, Ohio, a corporation of Maryland Filed Nov. 4, 1964, Ser. No. 408,968 3 Claims. (Cl. 6026.1)

The present invention relates to explosive type motors and, more specifically, to an explosive type motor having a piston member positive locking feature.

There are many applications in which high-speed operation of selected devices is required. One method of producing high-speed mechanical acting force is an explosive motor. Devices of this type are very similar to ordinary cartridges, in that a piston member which is axially movable within the bore of a cylinder member is rapidly actuated by the firing of an explosive charge. One disadvantage which has been found with motors of this type is that the piston tends to rebound into its original position after the charge has been fired. In some applications, this feature is highly undesirable.

Therefore, it is the object of this invention to provide an improved explosive motor having a piston member positive locking feature wherein the piston member is positively locked in its fired position, thereby eliminating the problem of mechanical rebound.

In accordance with this invention, an explosive motor piston locking arrangement is provided wherein a deformable material cylindrical member is distorted into triangular cross-section grooves contained about the circumference of both the piston surface and the interior wall surface of the bore of the barrel member, thereby pennanently, securely, and positively locking the piston member in its fired position.

For a better understanding of the present invention, together with additional objects, advantages, and features thereof, reference is made to the following description and accompanying drawings, in which:

FIGURE 1 is a cross-sectional View of an explosive type motor incorporating the features of this invention, showing the piston member in the unfired position, and

FIGURE 2 is a cross-sectional view of an explosive type motor incorporating the features of this invention, showing the piston member in the fired position.

Referring to FIGURE 1, an axially-movable piston member is located within the bore 11 of a barrel member 12. The end 13 of the bore of the barrel member 12 is open to the atmosphere, while the opposite end is securely closed with a top member 14 including a percussion cap 15. This percussion cap may be any one of the several well known in the art and may be mechanically or electrically actuated. The volume 20 between the cap 15 and the top of the piston 10 is filled with an explosive charge material which may be ignited by the operation of the percussion cap 15.

As the charge in the volume explodes, the piston 10 is violently driven in an axial direction within the bore 11 of the barrel 12, in a direction away from the percussion cap 15, much as a projectile is propelled from a fixed ammunition shell. To provide a gas seal between the bore of the barrel 12 and the circumferential surface of the piston 10, a conventional O ring seal 21 may be employed.

As the piston 10 is axially moved by the exploding charge contained in the volume 20, the shoulder is forced against the ledge 31 extending circumferentially about the wall of the bore 11 in the barrel 12. In prior art devices, the resiliency of the metal used for the motor was sufficient to overcome the frictional forces of the O ring 21 and the surface of the piston 10 against the wall 3,234,727 Patented Feb. 15, 1966 surface of the bore 11 and caused the piston. 10 to rebound axially in the opposite direction toward the percussion cap 15. In many applications, this feature is undesirable.

In accordance with the novel features of this invention, the piston member positive locking feature comprises a first groove 32, which is of a triangular cross-section and extends circumferentially around the surface of the piston 10, a second groove 33, which is of triangular cross-sect1on and extends circumferentially around the wall surface of the bore 11, and a cylinder member of deformable material 35 disposed about the piston 10.

It may be noted that one leg of each of the triangular grooves 32 and 33 is positioned substantially normal to the longitudinal axis of the bore 11 of the barrel 12, and the apices of the triangles are situated in a direction opposite each other. This is the preferred configuration; however, other similar configurations may be used without departing from the spirit of this invention.

Disposed around the piston 10 is a cylindrical locking member 35, of a deformable material, having two open ends. This cylindrical locking member may be of a lead or a similar deformable material and is located in such a manner as to be substantially between the groove 32 in the piston 10 and the groove 33 in the barrel 12 when the piston 10 is in its unfired position.

As the piston 10 is driven axially under the influence of the exploding charge contained in the volume 20, the shoulder 36, extending about the circumference of the piston 10, engages the deformable material cylindrical member 35 and distorts the material of this member into the groove 32 in the piston 10 and into the groove 33 of the barrel 12, as indicated in FIGURE 2.

This distortion of the deformable material cylinder 35 into the grooves 32 and 33 positively locks the piston 10 in its fired position and prevents the undesirable rebound which is present in prior art devices of this type.

While a preferred embodiment of the present invention has been shown and described, it will be obvious to those skilled in the art that various modifications and substitutions may be made without departing from the spirit of the invention, which is to be limited only within the scope of the appended claims.

What is claimed is:

1. In an explosive motor of the type having a piston member which is axially movable, under the influence of an ignited explosive charge, within the bore of a cylinder member, the piston positive locking feature comprising a first groove extending circumferentially around the surface of said piston member, a second groove extending circumferentially around the wall surface of said bore of said cylinder member and axially displaced from said first groove when said piston is in the unfired position, a cylindrical locking member of deformable material having two open ends disposed around said piston member and between said first and second grooves when said piston member is in the unfired position, and a shoulder extending around the circumference of said piston member arranged to engage and deform said cylindrical locking member into said grooves when said piston member is axially moved by an ignited explosive charge.

2. In an explosive motor of the type having a piston member which is axially movable, under the influence of an ignited explosive charge, within the bore of a cylinder member, the piston positive locking feature comprising a first triangular cross-section groove extending circumferentially around the surface of said piston member, a second triangular cross-section groove extending circumferentially around the wall surface of said bore of said cylinder member and axially displaced from said first groove when said piston is in the unfired position, a cylindrical locking member of deformable material having two open ends disposed around said piston member and between said first and second grooves when said pitson member is in the unfired position, and a shoulder extending around the circumference of said piston member arranged to engage and deform said cylindrical locking member into said grooves when said piston member is axially moved by an ignited explosive charge.

3. In an explosive motor of the type having a piston member which is axially movable, under the influence of an ignited explosive charge, within the bore of a cylinder member, the piston positive locking feature comprising a first triangular cross-section groove having one leg thereof positioned substantially normal to the longitudinal axis of said bore of said cylinder member extending circumferentially around the surface of said piston member, a second triangular cross-section groove having one leg thereof poistioned substantially normal to the longitudinal axis of said bore of said cylinder member extending circumferentially around the wall surface of said bore of said cylinder member and axially displaced from said first groove when said piston is in the unfired position, a cylindrical locking member of deformable material having two open ends disposed around said piston member and between said first and second grooves when said piston member is in the unfired position, and a shoulder extending around the circumference of said piston member arranged to engage and deform said cylindrical locking member into said grooves when said piston member is axially moved by an ignited explosive charge.

No references cited.

MARK NEWMAN, Primary Examiner.

FRED E. ENGELTHALER, Examiner. 

1. IN AN EXPLOSIVE MOTOR OF THE TYPE HAVING A PISTON MEMBER WHICH IS AXIALLY MOVABLE, UNDER THE INFLUENCE OF AN IGNITED EXPLOSIVE CHARGE, WITHIN THE BORE OF A CYLINDER MEMBER, THE PISTON POSITIVE LOCKING FEATURE COMPRISING A FIRST GROOVE EXTENDING CIRCUMFERENTIALLY AROUND THE SURFACE OF SAID PISTON MEMBER, A SECOND GROOVE EXTENDING CIRCUMFERENTIALLY AROUND THE WALL SURFACE OF SAID BORE OF SAID CYLINDER MEMBER AND AXIALLY DISPLACED FROM SAID FIRST GROOVE WHEN SAID PISTON IS IN THE UNFIRED POSITION, A CYLINDRICAL LOCKING MEMBER OF DEFORMABLE MATERIAL HAVING TWO OPEN ENDS DISPOSED AROUND SAID PISTON MEMBER AND BETWEEN SAID FIRST AND SECOND GROOVES WHEN SAID PISTON MEMBER IS IN THE UNFIRED POSTION, AND A SHOULDER EXTENDING AROUND THE CIRCUMFERENCE OF SAID PISTON MEMBER ARRANGED TO ENGAGE AND DEFORM SAID CYLINDRICAL LOCKING MEMBER INTO SAID GROOVES WHEN SAID PISTON MEMBER IS AXIALLY MOVED BY AN IGNITED EXPLOSIVE CHARGE. 